The invention relates to a height-adjustable underframe of a vehicle seat with a left and a right couple of rails of a longitudinal adjusting device and with a left and a right side part that are each hinge-connected to the corresponding seat rail of the couple of rails by way of a rear and a front pivoting arm.
Height-adjustable underframes of this type have been known in many kinds of embodiments. Each seat side constitutes a four-bar linkage. Said four-bar linkage is adjusted and locked by designing one joint in such a way that it may be adjusted and locked, for instance by means of a sector gear that is concentric with the joint and of a pinion that is in engagement with said sector gear. Adjustment and locking may be carried out by way of a drive, mostly an electric motor, or by hand. One is anxious to arrange the adjusting and locking device on the side part. As a result thereof, it always remains in the same position relative to a passenger when it is hand-controlled.
One is also anxious not to position the adjusting and locking device too far backward, more specifically not in the region underneath a seat back of the vehicle seat, but rather to the front, toward the front edge of the seat. It is thus more conveniently within reach for a passenger.
The invention proceeds from these considerations. It is its object to develop the underframe of a vehicle seat of the type mentioned herein above in such a way that the stopping device, which provides for the adjustment and the locking functions, may be arranged quite far to the front, in any case preferably in front of the longitudinal center of the side parts. This makes it possible to save space in the rear region of the seat, underneath the seat back. The actuators for the stopping device may be arranged so as to be conveniently within reach.
In view of the height-adjustable underframe of the type mentioned herein above, the solution to this object is to provide a blocking arm that is linked by a lower end region to the corresponding seat rail on the hinge point of a rear pivoting arm and that is detachably fixed in proximity to its upper end in a stopping device, which is fastened on the corresponding side part.
The blocking arm is almost oriented on a diagonal in the four-bar linkage which is formed by the seat rail, the rear pivoting arm, the side carrier and the front pivoting arm. As a result thereof, the four-bar linkage is considerably stiffer in stopped condition than when only one of the four joints is being blocked. The stopping device may be arranged on differential locations of the side part, a handy position for hand-control may be achieved thereby, an optimum position may also be found for a motor-driven adjustment. One is thereby freed from the actual hinge point, so that space for components can be saved or used otherwise.
In a preferred embodiment, the blocking arm is provided with teeth in the region of its upper, front end and the stopping device has a pinion that is rotatably carried in bearings in the corresponding side part. A stopping device that is easy to operate and reliably locking is thus achieved with simple means.
In an alternatives embodiment front end of the blocking arm can be realized as a stopping device comprising a spindle, and a rotatable nut, which receives said spindle, is fixed on the side part.
In a particularly preferred embodiment, the stopping device is arranged in proximity to the hinge point of the front pivoting arm on the corresponding side part. As a result, a relatively great length of support is provided by the blocking arm. It is furthermore now possible to arrange the front and rear pivoting arms of the seat side in one plane and to accommodate the blocking arm in a plane offset relative thereto. Accordingly, the blocking arm is a plane part. It is oriented parallel to the corresponding side part.
In another, preferred embodiment, the blocking arm has a guiding area that faces its teeth. There is provided a guide element which is fastened on the corresponding side part opposite the pinion. In this way, the blocking arm is guided between pinion and guide element. The result thereof is a functional realization that is suitable for practical utilization. Said realization is advantageously further developed in that the upper end of the blocking arm is encircled in the form of a ring in the region of the stopping device.